Diakóptis
by Samantha Novak
Summary: The angels have their eyes on a powerful object they know is hidden in a cave system somewhere. Of course they send Castiel to get it. Of course he asks the Winchesters for help, never intending to let the angels have it. Of course things don't go as they planned. The very object they're searching for casts a spell over Sam and Castiel, siphoning the angel's grace into the hunter.


**AUTHOR'S NOTE:** _Fill for the following prompt from the LJ SPN Kink Comm._

 _"A magical object puts Cas's Grace in Sam. Sam gets the chance briefly to protect Cas the way he always should have been._

 _Bonus for Sam having to smite some demons and covering Cas's eyes with his hand to protect him."_

diakóptis _\- v. Greek. "switch."_

* * *

"What are we looking for again?" Dean grumbled, using the hand not clutching Ruby's knife to wipe sweat from his forehead. They'd been walking for over an hour and while he wasn't out of shape, they hadn't _stopped_ walking and they were cramped together and in a confined space.

"It is called the Diakóptis," Cas said, pausing at an intersection in the tunneling before deciding to go right, leading the Winchesters down that passage. He swept the flashlight in one hand – his angel blade was gripped in the other- across the space in front of them but the stone looked just the same as it had for the last hour they'd been down there.

"And what does this thing even _do?_ " Sam added, reaching a hand to his back to try to rub out the ache in his lower back from stooping for so long. Caves were not meant for anyone over six feet.

"All we know is that has powerful magic and we will all be safer if the demons don't get it," Cas muttered, pausing to eye a section of stone that looked slightly different than the stone around it. When he deemed it useless, he continued moving.

"Okay, and do you know what this thing even _looks_ like?" Dean snapped, patience running thin. So far, all Cas had told them was that the angels got wind of some ancient artifact hidden in a cave somewhere in the mountains and that they wanted it before the demons could find it. Of course, even _Cas_ had no plans of giving the artifact to his siblings. _If_ they ever found it, it would get tucked in a warded box in the bunker somewhere for safekeeping.

"I know it's made of stone," Cas answered in a tone that made it obvious how tired of the constant questions he was becoming.

"Great," Dean muttered. "Like looking for a needle in a haystack."

"Wouldn't that be easy?" Cas asked, pausing to turn around to tilt his head at the Winchester, brows furrowing in obvious confusion. "A needle would stand out in a haystack. The Diakóptis is stone so it would blend in to the stones here. Wouldn't the correct metaphor be 'Looking for a needle in a stack of needles'?"

"That's not-" Dean huffed when he couldn't come up with a proper retort then growled, "It's just an expression, Cas. Keep moving."

Cas's confused expression didn't lighten up as he turned around again to continue moving down the passage.

"Cas, does this thing have any kind of writing or symbols on it?" Sam asked from his place in the back of the line. "I mean, what makes this thing so powerful?"

"I don't know what gives it its power," Cas admitted, pausing once again to examine another intersection. "But we must find it."

"Do you even know where you're going?" Dean snapped as he followed the angel down another tunnel. "How are you choosing which ways to go?"

"I have excellent sense of direction, even in a labyrinth such as this," Cas countered, a slight edge of defensiveness in his tone. "I know exactly where we are in relation to the entrance and where we have already covered. I will not take us down the same path twice."

Dean didn't say anything in response, only vaguely humming in acknowledgment as he followed the angel. They continued in this manner for what felt like another hour to the hunter before Cas's pace quickened around a bend in the tunnel. When the two hunters followed, they saw an opening in the cave, almost like a perfectly carved out room in the stone. It was littered with rocks and debris, all of the stones looking exactly the same to the humans.

"It's in here," Cas announced, stepping forward and narrowing his eyes at the amount of stones littering the cavern floor. "I can feel it. But I can't pinpoint _where_..."

Dean rolled his eyes. Of course it would be in the room with a ton of other rocks. It wouldn't be hidden well if it were just lying on a tunnel floor. "How are we going to find it when you're the only one that knows what it looks like?"

"You don't have to. When it is uncovered, the… _signal…_ it emits to magical beings will become stronger. I will be able to sense when we have found it," Cas explained.

"Okay," Dean said slowly then sighed. "Well, let's get digging."

They each chose a place to start and began clearing away debris. After ten minutes of digging through piles of rocks, the hunters' hands were smeared with dirt and, in some places, blood where more jagged rocks had cut into their skin. Just as Dean was reaching the cavern floor in his section of debris, Cas quickly stood and crossed toward where Sam had been digging.

"I can feel it," he said, kneeling to help Sam, dropping his angel blade beisde where he crouched. "You've uncovered enough of it that I can narrow down its presence in this room. It is somewhere over here..."

Hope renewed, Sam began clearing away rocks quicker, more of his palms acquiring small cuts that he hardly noticed. Even Cas managed to acquire a few scrapes to his palms as they dug but the angel paid them no mind; he'd use his grace later to mend the wounds. Then, just as Sam pushed away another useless rock and grasped the next one, his eyes widened.

"Cas, pretty sure this is it," he said, scrubbing a palm across the dirt covered engravings on the stone he'd just unearthed.

"It is," the angel announced, reaching a bleeding palm down to grasp the rock as Sam lifted it up.

As soon as Cas's hand made contact with the stone, the runes carved onto it began glowing brightly. Sam had to turn away from it as it shone too bright to look at it. He heard Cas let out what sounded like an agonized groan then Dean calling their names. Then he felt like the hand in contact with the stone was being electrocuted and his grip on it loosened enough that the stone fell back into the debris they'd uncovered it from. The tingling in his hand spread further up his arm and he felt sweat bead on his forehead and upper lip as his body temperature rose.

Just as quickly as the light filled the cave, it faded and Sam opened his eyes, immediately seeking out their angel, almost expecting to find him unconscious across the room. Instead, Cas was in the same place he was when the light engulfed the room. His hand still hovered in mid air where they had been holding the stone, but his eyes were focused on Sam, wide and almost panicked.

"Cas?" Sam panted, reaching a still shaking hand toward their angel in an attempt to comfort but Cas flinched away from the touch. "Cas, you okay?"

"What the hell was that?!" Dean snarled as he scrambled across the room toward them. "You both touched the rock and then I had to look away or risk my eyes melting!"

"I-" Cas started then swallowed, eyes narrowing in scrutiny as he leaned slightly closer to Sam. "I think… I know what the Diakóptis does. Our palms… we were both bleeding. Sam, look at your hands."

"My…?" Sam furrowed his brow in confusion but looked down at both palms… which were now clean and cut-free. "How…? Cas, did you…?"

Cas shook his head. "I did not touch you, Sam. The Diakóptis… When the light filled the cave, did you feel anything new?"

"Um… my hand kinda tingled like I was being electrocuted and then it moved up my arm and I felt hot," Sam said.

"I thought so… Sam, I think it took my grace and gave it to you," Cas said. "The engravings on the stone – they're a spell. A changing spell. When both our bloods touched the stone, I think it activated and used that as a point A and B, if you will, to… _switch_ us."

"But… this isn't like when an angel possess a vessel, is it? I mean, that's not _you_ in there, right? You're still _here_ ," Dean said, eyeing Sam curiously.

Cas shook his head. "No, I'm still me and Sam is still Sam. For all intents and purposes, I am human and Sam is now an angel."

"It's not gonna hurt me, is it?" Sam asked, a slight edge of fear lacing his voice. His hands were still held out in front of himself where he'd been examining them as if Cas's grace would hurt him if he moved.

Cas immediately shook his head. "No, of course not. You were both born to be vessels. You can withstand angelic grace."

"How do we give it back?" Sam asked, finally lowering his hands. "No offense, Cas, but I don't want your grace."

Despite of the current situation, Cas smiled and huffed a breathy laugh. "None taken. I would rather I have my grace, too."

"Can't you guys just touch it again and then it'll do the point A and B thing and switch you back?" Dean asked.

Cas frowned as he eyed the stone then returned his gaze to Sam. "I am willing to try if you are."

Sam nodded. "Let's try it."

They each took hold of either end of the stone but unlike the last time, no light filled the room. Sam didn't feel any tingling or heat, nor did Cas. The two stared at each other in confusion while Dean glared at the stone as if it had personally wronged him by not changing his brother and their angel back to normal.

"It can only be activated by the same two people once," a cool, feminine voice said from the entrance of the cave.

All three men stood to see a blond woman in jeans and a form-fitting blouse standing in the cave entrance. She had one hand on her hip and her red painted lips curled up in a sneer. Behind her, two large men stood, arms crossed and glaring at the Winchesters and their angel. Clearly, this woman was the leader.

As soon as Sam turned his gaze to the three newcomers, he recoiled closer to Cas. "Their… Their faces! I can see through their meatsuits – they're demons."

"Like when I was close to the end of my deal," Dean whispered. "You can see the ugly behind the mask."

"It is because of my grace," Cas explained.

"You see this all the time?" Sam asked, horrified.

"Yes."

"Enough!" the woman snapped. "Hand over the Diakóptis. It is no more use to you."

"No," Cas growled, tucking the bloodied stone into his trench coat's inside pocket then snatching up his blade. "Even if we cannot use it to reverse this, it is still better with us than _you_."

The woman smirked and shifted her weight so she was standing upright. "You have too much confidence for someone who just lost all their powers."

"I have been human before. I know how to fight without my grace," Cas growled, running at her with his blade up. He managed a swipe to her shoulder before she used her powers to fling him across the room, snarling as she eyed the cut to her shoulder.

"You're all talk and no game," she sneered. "You're no match for me without your grace, angel boy."

"Maybe he's not, but I am!" Dean growled, brandishing the demon knife and charging at one of the female demon's cronies. He managed a solid stab to the chest before the other large man slammed into him. Despite being knocked on his ass, Dean still smirked as the first male sparked orange light behind his eyes before crumpling to the ground.

"You!" the woman snarled. "You Winchesters are a pain the collective asses of demonkind, you know that?!"

While Dean had attacked the one male demon, Sam had quietly crept across the cave to Cas's slumped form. He gently shook the angel – human? – and sighed with relief when Cas groaned and stirred.

"Cas," Sam breathed. "You're okay."

Cas winced and gingerly touched the back of his head, relaxing when his fingers came back clean. "I'm fine," he croaked as he pushed himself to his feet then picked up his angel blade.

"Not for long," the woman growled, giving her remaining companion a look. It must have been some kind of silent order because he was immediately crossing the room toward the two.

"Stay behind me," Sam instructed, putting one arm out across Cas's chest and widening his stance as he glared at the approaching demon.

"Please," the demon sneered, not ceasing his approach. "What are _you_ gonna do?"

As soon as he was within arm's reach, Sam slapped a palm to the demon's forehead, willing the grace inside him to do what he wanted it to. He'd seen Castiel smite demons a thousand times and if he could just command the grace like Cas made it seem so easy to do… His palm began to heat up but it wasn't an uncomfortable burn that he couldn't handle. Then the demon's eyes and open mouth began to glow grace blue and Sam huffed a relived breathe, grinning as he felt (his?) grace burning through the demon.

"Shut your eyes!" Sam commanded, reaching back with his free hand to pull the smaller man into his side, feeling Cas bury his face into Sam's chest.

Relieved Cas was safe, Sam let the grace surge forward, burning through the now screaming demon the way it did when Castiel smote demons. As the burned out body dropped to the floor, Sam stared with wide eyes, mouth agape in awe.

"I did it," he breathed. "Cas, I-"

The remaining demon let out an ear piercing screech of rage, eyeing the second fallen demon. "You will _pay_ for this!" she snarled.

"Yeah?" Dean countered, smirking as he ambled his way toward Sam and Cas, eyes never leaving the demon. "You lost your little henchmen to a human with a knife and a human that just happens to have newly acquired grace that he doesn't know how to control. You really wanna take the chance that you won't end up kabobbed or burnt to a crisp?"

The demon sneered at him but took a step back toward the opening of the cave. "This isn't the end," she warned. "Crowley wants the Diakóptis. He won't stop until he gets it."

"Yeah?" Dean countered, grinning boyishly. "Well, you tell Crowley if he wants this stone, he can come get it himself. 'Cause we're just gonna take out any of you littler demons he sends for us."

The woman snarled derisively but didn't try arguing. Instead, she turned and hastily made her way out of the tunnels.

Dean glared at the empty entrance for a second longer before turning back to Sam and Cas. "How the hell did you do that?"

"I have no idea," Sam said, one arm still wrapped around Cas's shoulders. "I just knew that I wanted to stop the demon from hurting Cas again and I just… imagined when Cas smites demons, and…" He shrugged.

"Thank you, Sam," Cas said quietly, making no move to step away from the hunter.

"'Course," Sam huffed with a sheepish smile, slipping his hand from around Cas to clap him on the back before stepping away.

"Okay, let's get outta here," Dean announced, hefting the demon knife in his hand. "We'll take the stone with us and figure out how to switch you back later."

"I can't lead us out," Cas offered up, sounding almost ashamed for admitting weakness. "My grace is what helped me orient myself no matter where I was."

"Couldn't I?" Sam asked.

"Hey, wait, how did you get your grace back after Metatron took it?" Dean asked. "The first time you came back when we got Gadreel outta Sam."

"I took another angel's grace," Cas said. "It wasn't _mine_."

"Okay, but you had to get it out of him and into you. How'd you do it?"

"I-" Cas's eyes narrowed as he looked down at the angel blade in his hand then back to Sam. "It might work…"

"What?" Sam asked hesitantly, not liking the way Cas had looked as his blade.

"If I cut you with an angel blade, the wound will leak grace. I can collect it then… consume it myself," Cas explained.

"You just have to make a cut?" Sam clarified.

Cas nodded. "As soon as I am an angel again, I will heal the cut we made. You will be perfectly safe."

Sam nodded once in clear agreement. "Okay. I trust you, Cas. Do we have anything to hold it in? We didn't know we'd take as long as we did to find the stone. We don't have any water bottles or anything."

Dean shook his head. "I didn't bring anything but the knife. Now that I know how long it took to get in here, I'm kinda wishing I brought some water or something to eat."

Sam turned back to Cas, mouth set in a determined line. "If we don't have anything to hold it in, can you take it straight from me or should we try to get out of here first and switch back later?"

"We could try that way," Cas said slowly, thinking it through as he agreed to it. "But you've seen what happens when an angel gains its grace. It will be bright and hot and there will only be a small window to back away from me once I've taken my grace back. That is why I prefer using some kind of containment – so you can get to a safe distance beforehand."

"I don't think I can get us out of here like you led us in," Sam admitted. "Let's do this. I trust you," he repeated.

"Alright," Cas agreed on a defeated sigh, squaring his shoulders. "Dean, back away. As soon as I have consumed my grace, I will give Sam a push to let him know he needs to move. This will be safe if _you_ are already out of the way."

Dean nodded and scurried away so his back was to the cave wall though his eyes remained laser focused on Sam and Cas.

"Give me your arm," Cas ordered as soon as Dean was safely on the other side of the cave, holding out his free hand to Sam.

Sam lifted his arm and let Cas gently grasp it, watching as the other man pushed up the sleeves of his coat and flannel to bare his forearm. Cas met his eyes when he placed the the edge of his angel blade to Sam's skin so Sam nodded, silently reassuring him that he was okay with this. As Cas slide the blade across his skin, he hissed at the sting of the cut being made, his eyes widening in wonder as the blue of grace shone from the wound. Cas dropped his blade, firmly gripped Sam's arm in both hands to hold him steady, then parted his lips and lowered his face toward the wound. He never made contact though, the grace seemingly eager to return to its rightful host. As soon as the last traces of grace left the wound, Cas shoved Sam back, stumbling back himself. As light shone from the center of Cas's chest and quickly filled the room, Sam and Dean squeezed their eyes shut and shielded them with their arms.

"You may look," Cas said a few seconds later. When they uncovered their eyes, he stood in the center of the room, tall and proud, hands healed and clean. His lips curled up into a small smile as he turned to Sam. "Give me your arm."

Sam held his arm out and watched Cas's palm pass over the cut. He felt the familiar tingle he always felt when Cas healed them but it felt more _right_ than the tingle of the grace thrumming through his body. "Thanks," he said with a smile. "I definitely prefer you having your grace than me."

"As do I," Cas said not unkindly with a small smile. "You handled it well though, Sam. I am proud of you."

"Thanks," Sam said sheepishly, ducking his head.

"Okay, let's get outta here," Dean announced. "I'm starving!"

* * *

 **AUTHOR'S NOTE:** _I take no credit for the "_ _needle in a haystack/needle in a_ _stack of needles" conversation in the beginning – I blatantly pilfered that theory from a conversation between Morgan and Reid from_ Criminal Minds, _hehe._


End file.
